1. Field of the Invention
This invention relates to imaging and range finding devices and methods. More particularly, this invention relates to devices and methods for imaging and range finding over very wide angular fields of view and at standard picture frame frequency.
2. Description of the Prior Art
Imaging devices are systems which depict predetermined fields of view and include such things as video cameras and television monitors. Range finding devices determine the distance between an object and the device and include such items as radar. Accordingly, an imaging range finder both images and range finds an object.
One example of an imaging device is Laakmann, U.S. Pat. No. 4,349,843, which discloses a television compatible thermal imaging system. That device scans thermal radiation emitted from objects, processes the radiation and displays a television picture of the scene. It is also capable of showing the scene at the standard picture frame frequency of 30-hertz set forth by the National Television System Committee ("NTSC"). However, it cannot scan an angular field of view greater than 51-degrees in the horizontal direction. Additionally, that device does not range find.
Range finding devices often require an object to be viewed from two different locations. For example, Merchant, U.S. Pat. No. 4,635,203, discloses a method for measuring range in which one view of an object is made to coincide with a second view taken of the same object from a different location. By calculating the transformation coefficients which will make the two images coincide, range may be determined.
Similarly, in Brown, U.S. Pat. No. 4,591,987, a video range finder is described which displays a split image of an object on a video monitor. By computing the tangent of the angle between the split images when the images are properly positioned, and if the true vertical dimension of the object is known, the range to the object may be calculated. That procedure does not require the object to be viewed from two different locations.
Present-day systems are not capable of simultaneously imaging and range finding at the NTSC standard television picture frame frequency of 30-hertz or at the International Radio Consultavie Committee ("CCIR") standard frequency of approximately 25-hertz. In other words, present-day systems cannot televise a scene and update frames of that scene at such standard frequencies while simultaneously determining the distance to the objects in the scene.
Additionally, present-day imaging and range finding devices cannot scan a wide angular field of view. Imaging devices such as video cameras generally have a horizontal angular field of view of less than 45-degrees. For wide angle optics, lenses such as fisheye lenses are normally required.
This invention overcomes the limitations of the prior art because it is capable of imaging and range finding over a very wide angular field of view at standard picture frame frequencies.